ABSTRACT ACKNOWLEDGEMENTS NOMENCLATURE Chapter 1 Introduction 1.1 Types of Embankment Dam 1.2 Hydraulic Fracturing 1.3 Failure of Teton Dam 1.4 Erosion Damage of Balderhead Dam 1.5 Leakage of Hyttejuvet Dam 1.6 Technical Route of Present Study Chapter 2 Literature Review 2.1 Theories of Hydraulic Fracturing 2.1.1 Theories Based on Circular Cavity Expansion Theory 2.1.2 Theories Based on Spherical Cavity Expansion Theory 2.1.3 Theories Based on True Triaxial Stress State Analysis 2.1.4 Empirical Formulas 2.1.5 Theories Based on Fracture Mechanics 2.2 Indoor Experimental Studies on Hydraulic Fracturing 2.3 Field Testing Studies on Hydraulic Fracturing 2.4 Model Testing Studies on Hydraulic Fracturing 2.5 Numerical Simulate on Hydraulic Fracturing 2.6 Summary Chapter 3 Conditions and Mechanisms of Hydraulic Fracturing 3.1 Conditions of Hydraulic Fracturing 3.1.1 Cracks Located at Upstream Face of Core 3.1.2 Low Permeability of Core Soil 3.1.3 Rapid Impounding 3.1.4 Unsaturated Soil Core 3.2 Mechanical Mechanism of Hydraulic Fracturing 3.3 Summaries and Conclusions Chapter 4 Fracture Toughness and Tensile Strength of Core Soil 4.1 Introduction 4.2 Tested Soil 4.3 Testing Technique on Fracture Toughness 4.3.1 Testing Method 4.3.2 Apparatus 4.3.3 Testing Procedures 4.3.4 Testing Program 4.4 Testing Results on Fracture Toughness 4.4.1 Suitability of Linear Elastic Fracture Mechanics 4.4.2 Influence Factors on Fracture Toughness 4.5 Testing Technique on Tensile Strength 4.5.1 Testing Method and Apparatus 4.5.2 Calculation on Tensile Strength 4.5.3 Testing Procedures 4.5.4 Testing Program 4.6 Testing Results on Tensile Strength 4.6.1 Water Content 4.6.2 Dry Density 4.6.3 Preconsolidation Pressure 4.7 Relationship Between Fracture Toughness and Tensile Strength 4.8 Discussion 4.8.1 Soils from References 4.8.2 Rocks from References 4.9 Summaries and Conclusions Chapter 5 Fracture Failure Criterion for Core Soil Under Mixed Mode 5.1 Introduction 5.2 Experimental Technique 5.2.1 Loading Assembly 5.2.2 Calculation Theory 5.2.3 Testing Procedures 5.2.4 Test Program 5.3 Testing Results 5.4 Fracture Failure Criterion 5.5 Summaries and Conclusions Chapter 6 Hydraulic Fracturing Criterion 6.1 Introduction 6.2 Failure Criterion 6.2.1 Simplification of Crack 6.2.2 Criterion 6.3 Cubic Specimen with a Crack 6.3.1 Calculation of KI 6.3.2 Calculation of Kn 6.3.3 Calculation of (Kq-KZn)0.s 6.3.4 Dangerous Crack Angle 6.4 Core with a Transverse Crack 6.4.1 Calculation of KI 6.4.2 Calculation of Ku 6.4.3 Calculation of (KZr +KZa )0s 6.4.4 Dangerous Crack Angle 6.5 Core with a Vertical Crack 6.6 Strike-Dip of Crack Spreading Easiest 6.7 Summaries and Conclusions Chapter 7 Numerical Method for Hydraulic Fracturing 7.1 Introduction 7.2 Theoretical Formula 7 2.1 Failure Criterion of Hydraulic Fracturing 7.2.2 Path of the Independent J Integral 7.2.3 Virtual Crack Extension Method 7.2.4 Calculation of J Integral 7.3 Numerical Techniques 7.3.1 Virtual Crack Aa 7.3.2 Finite Element Model 7.3.3 Water Pressure Applied on Crack Face 7.3.4 Judgement and Simulation of Hydraulic Fracturing 7.4 Numerical Investigation 7.4.1 Finite Element Model 7.4.2 Virtual Crack Depth Aa 7.4.3 Mechanical Parameters of Crack Material 7.5 Numerical Verification 7.5.1 Mode Crack 7.5.2 Mode ]1 Crack and Mixed Mode Crack 7.6 Summaries and Conclusions Chapter 8 Factors Affecting Hydraulic Fracturing 8.1 Introduction 8.2 Factors Affecting Stress Arching Action 8.2.1 Influence of Material Properties 8.2.2 Influence of Dam Structure 8.3 Relation Between Hydraulic Fracturing and Arching Action 8.4 Factors Affecting Hydraulic Fracturing 8.4.1 Analyzing Method 8.4.2 Influence of Water Level 8.4.3 Influence of Crack Depth 8.4.4 Influence of Crack Position 8.4.5 Influence of Core Soil Features 8.5 Summaries and Conclusions Chapter 9 Simulation on Nuozhadu Dam 9.1 Introduction to Nuozhadu Dam 9.2 Behavior of Stress-Deformation of Nuozhadu Dam 9.2.1 Finite Element Model 9.2.2 Material Parameters 9.2.3 Behavior of Stress-Deformation After Construction 9.2.4 Behavior of Stress-Deformation After Filling 9.3 Analyzing Method of Hydraulic Fracturing of Nuozhadu Dam 9.3.1 Analyzing Method 9.3.2 Material Parameters 9.3.3 Finite Element Model 9.3.4 Schemes Analyzed 9.4 Hydraulic Fracturing in Horizontal Cracks 9.5 Hydraulic Fracturing in Vertical Cracks 9.6 Summaries and Conclusions References